Method and device for transmitting safety-critical operating conditions of a motor vehicle

ABSTRACT

The present invention relates to a method for transmitting a safety-critical operating condition of a safety-critical system of a motor vehicle to the driver, and a device for implementing the method. Transmission of a safety-critical operating condition to the driver by means of a control lamp can be disrupted if the control lamp is broken or the driver ignores the control lamp. To this end, measures are provided which reduce the driving comfort of the driver and draw his attention to the safety-critical operating condition.

TECHNICAL FIELD

The present invention generally relates to a method for transmittingsafety-critical operating conditions and more particularly relates to amethod for transmitting a safety-critical operating condition of asafety-critical system of a motor vehicle to the driver of a vehicle.

BACKGROUND OF THE INVENTION

DE 199 61 871 A1 discloses a driver information system detecting severaloperational data of a motor vehicle by means of a control unit anddefining a priority in terms of the relevance of the operational datafor the driver and transmitting it to the driver by means of a signal.It is considered a shortcoming in the prior art driver informationsystem that a defect of the output unit drawing the driver's attentionto critical operating conditions by way of an optical and/or audiblesignal is not discovered.

BRIEF SUMMARY OF THE INVENTION

In view of the above, an object of the invention is to develop a methodof transmitting a safety-critical operating condition of a motor vehicleto the driver that operates reliably even if optical or acoustic outputunits are defective.

According to the invention, this object is achieved in that measures areprovided making the driver aware of the safety-critical operatingcondition by way of an impaired comfort. Further, it is thereby ensuredthat the driver cannot ignore optical and/or audible signals of anoperative output unit indicative of a safety-critical operatingcondition.

In a favorable improvement, the measures are taken on a temporallylimited basis and/or a recurrent basis, and the measures are carried outin consideration of the current driving situation. Due to these measuresresulting in loss in comfort it is unmistakably conveyed to the driverthat the motor vehicle suffers from at least one safety-criticaloperating condition.

To render the idea of the invention more precise, it is arranged for tocarry out the measures in consideration of the current drivingsituation, and the selection of the measures depends on the durationand/or the seriousness of the safety-critical operating condition asregards the safety of operation of the motor vehicle.

In a particularly favorable manner, the measures involve a deactivationof the internal combustion engine during standstill of the motor vehiclethat is unwanted by the driver or an actuation of the acoustic alarmdevice (horn) unwanted by the driver when the doors of the motor vehicleare opened and closed.

According to further favorable embodiments, the measures involve anoperation of the electric window lifters unwanted by the driver duringstandstill of the motor vehicle or a deactivation of the multimediadevice unwanted by the driver.

In a particularly advantageous embodiment the measures represent afaulty oil-level tell-tale or a faulty tank capacity tell-tale. Besides,the measures involve a raised temperature indication or an incorrectrotational speed indication of the internal combustion engine of themotor vehicle.

Further, the measures involve an actuation of the electricallyadjustable outside rearview mirrors or of the electrically adjustableseats during standstill of the motor vehicle being unwanted by thedriver.

According to another realization of the idea of the invention, themeasures involve switching on the dimmed headlight unwanted by thedriver or switching off the power steering system unwanted by thedriver.

In another favorable design of the subject matter of the invention, themeasures involve an additional signal in a brake system withelectronically adjustable brake forces which influences the desiredbrake force to such effect that a fluctuation in the longitudinaldeceleration can be detected which corresponds in its mean value perunit time to the desired brake force, however.

Besides, it is arranged for that the measures involve a change of thepedal-travel/brake-force characteristics.

The device of the invention for implementing the method provides acentral control unit sensing the safety-relevant operating conditionsand triggering measures. The central control unit can be integrated intoan instrument combination device.

BRIEF DESCRIPTION OF THE DRAWINGS

The only FIGURE represents a chronological order starting from thereport of a critical operating condition to the driver by means of anoptical or acoustic signal until the remedy of the critical operatingcondition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Methods for transmitting critical operating conditions of systems andsystem components of a motor vehicle are known from the state of theart. In general, an optical or an audible signal is produced and sent tothe driver when a system or a system component of the motor vehiclereaches a critical operating condition. If, for example, the anti-locksystem is defective or operative only within limits, this criticaloperating condition is transmitted to the driver by means of a so-calledsmall control lamp, with the control lamp mounted in the instrumentpanel lighting up in an enamel for signals. If the driver ignores thisalarm signal, or is the control lamp defective, the critical operatingcondition of a motor vehicle system is not transmitted to the driver,what leads to a substantial loss in the general traffic safety. Toensure the transmission of a critical operating condition of a motorvehicle system to the driver, according to the present invention,further measures are provided in addition to optical and audiblesignals, making the driver aware of the critical operating condition.The target of these measures is to considerably limit the drivingcomfort of the driver. This will induce the driver to see a workshop,and the critical operating condition can be removed professionally andshortly after the critical operating condition has occurred.

It is arranged for that the measures for reducing the driving comfortare carried out on a temporally limited basis and on a recurrent basis.This means that the provided measures are carried out once to beginwith, and within time limits and, if the driver does not feel compelledto seek advice in a workshop, will be recurrent with the progressiveoperating time of the motor vehicle and a continuing critical operatingcondition. Besides, the current driving situation is taken intoconsideration when executing the measures for reducing the comfort.Thus, the deactivation of the internal combustion engine unwanted by thedriver is performed as a measure for reducing the driving comfort onlyduring standstill of the motor vehicle in order not to adversely affectthe general safety.

One embodiment of the method of the invention is illustrated in thedrawing. The illustrated stretch of time mirrors the operating time ofthe motor vehicle. The anti-lock system of the braking system fails attime 101. This fact is conveyed to the driver at time 101 by means of anoptical signal of the control lamp. If the control lamp is defective orif the driver ignores the optical signal, a first measure for reducingthe driving comfort is initiated after another operating time of themotor vehicle of two hours. Starting from time 102, the internalcombustion engine is switched off during longer phases of standstill,e.g. while the driver is waiting to continue driving in front of a redlight. It is thus signaled to the driver that his motor vehicle ismalfunctioning. In addition, the driving comfort is limited by there-start of the internal combustion engine which must be performedmanually, what induces the driver to go to a workshop for eliminatingthe actual cause of the internal combustion machine disconnectingseveral times, i.e. the defective anti-lock system.

If the driver continues ignoring the obvious losses in comfort, a secondmeasure will be taken at time 103, meaning four hours after the firstmeasure has been initiated. To this end, the power steering system isdisconnected, what means a considerable loss in driving comfort for thedriver. However, the power steering is disconnected only afterdeactivation of the internal combustion engine, in order that the driverdoes not have to expect a changed expenditure of force for turning thesteering wheel during the current driving operation. If the driver nowas before does not seek help in a workshop, a third measure to reducethe driving comfort is initiated at time 104. To this end, the acousticwarning device (horn) is actuated in such a fashion that a short signalis generated as soon as the driver opens or closes the doors of themotor vehicle.

After another four hours of operating time, during which the threedescribed measures for reducing the driving comfort were effective, thedriver consults a workshop at time 105 and has the defective anti-locksystem repaired. The effect is that a critical operating condition of asystem or a system component no longer prevails in the motor vehicle,and the measures introduced for reducing the driving comfort arestopped.

The method of the invention arranges for further measures, which limitthe driving comfort of the driver and make him aware of thesafety-critical operating condition.

As this occurs, an activation of the window lifters unwanted by thedriver during standstill of the motor vehicle represents a reduction ofthe driving comfort exactly as the unwanted deactivation of themultimedia device of the motor vehicle. Another measure limiting thedriving comfort of the driver is realized by the actuation of theelectrically adjustable exterior rearview mirrors or the electricallyadjustable seats during standstill of the motor vehicle, which isunwanted by the driver. An activation of the dimmed headlight unwantedby the driver also represents a loss of the driving comfort for thedriver. Due to their effect on the driver, these measures areappropriate to make the driver notice a critical operating condition ofthe motor vehicle and induce him to see a workshop.

Further measures making the driver aware of the fact that his motorvehicle has a defect are achieved by means of a raised temperatureindication or a faulty rotational speed indication of the internalcombustion engine. A faulty oil-level tell-tale or a faulty tankcapacity tell-tale also indicate a critical operating condition of amotor vehicle system to the driver.

The measures being carried out for the purpose of warning the driver areselected in consideration of the duration of the safety-criticaloperating condition. If a safety-critical operating condition lastsbeyond a predetermined stretch of time, a measure is chosen which limitsthe driving comfort for the driver to a greater degree. This willexpressly indicate to the driver that he must see a workshop. Besides,the selection of the measures for reducing the driving comfort isdetermined in dependence on the seriousness of the safety-criticaloperating condition. A less serious safety-critical operating conditionwill consequently entail a less significant measure for reducing thedriving comfort than a safety-critical operating condition that takes adirect effect on the traffic safety.

In a motor vehicle having a braking system with electronicallyadjustable brake forces, the method of the invention provides that thebraking request of the driver is realized in a modified manner when asafety-critical operating condition shall be conveyed. To this end, anadditional signal is produced in an electronic control and regulationunit (hereinbelow referred to as ECU) provided in the braking system,which influences the desired brake force to such effect that the driverfeels a fluctuation of the longitudinal deceleration which in theaverage time value corresponds to the desired brake force, however. Thismodified realization of the brake force request also represents areduction of the driving comfort for the driver. Another measure fortransmitting a safety-critical operating condition to the driver isrealized by the change of the pedal-travel/brake-force characteristicsin a motor vehicle with electronically adjustable brake forces. In thisarrangement, the ECU changes the pedal-travel/brake-forcecharacteristics to which the driver is accustomed to such end that thedriver is limited in his driving comfort due to the unusual newoperation of the braking system.

To implement the method of the invention, a central control unit isprovided to which the safety-relevant operating conditions of thesystems or the system components of the motor vehicle are sent. Startingfrom this central control unit, the appropriate measure for thereduction of the driving comfort is chosen, as has been described indetail, and the control unit of the system related to the measure isactuated accordingly. It is especially favorable that the centralcontrol unit is integrated into the instrument combination devicebecause in this case the safety-critical operating conditions inprior-art driver information systems are sent to the driver by means ofthe known control lamps. Starting from the delivered safety-criticaloperating conditions, the measures for reducing the driving comfort canbe reliably initiated.

However, it is also possible to initiate the methods for reducing thedriving comfort in a decentralized fashion. This implies that eachsystem having a safety-critical operating condition will directlyintroduce measures for reducing the driving comfort. The above-mentionedbraking system with electronically adjustable brake forces willconsequently carry out the modified realization of the braking requestof the driver or a change in the pedal-travel/brake-forcecharacteristics when a safety-critical operating condition occurs.

1-17. (canceled)
 18. A method for transmitting a safety-criticaloperating condition of a safety-critical system of a motor vehicle tothe driver, wherein measures are provided making the driver aware of thesafety-critical operating condition by way of an impaired comfort. 19.The method as claimed in claim 18, wherein the measures are taken on atemporally limited basis and/or a recurrent basis.
 20. The method asclaimed in claim 18, wherein the measures are carried out inconsideration of the current driving situation.
 21. The method asclaimed in claim 18, wherein the selection of the measures depends onthe duration and/or the seriousness of the safety-critical operatingcondition as regards the safety of operation of the motor vehicle. 22.The method as claimed in claim 18, wherein the measures involve adeactivation of the internal combustion engine unwanted by the driverduring standstill of the motor vehicle.
 23. The method as claimed inclaim 18, wherein the measures involve an actuation of the acousticalarm device (horn) unwanted by the driver when the doors of the motorvehicle are opened and closed.
 24. The method as claimed in claim 18,wherein the measures involve an operation of the electric window liftersduring standstill of the motor vehicle what is unwanted by the driver.25. The method as claimed in claim 18, wherein the measures involve adeactivation of the multimedia device unwanted by the driver.
 26. Themethod as claimed in claim 18, wherein the measures involve a raisedtemperature indication or an incorrect rotational speed indication ofthe internal combustion engine of the motor vehicle.
 27. The method asclaimed in claim 18, wherein the measures represent a faulty oil-leveltell-tale or a faulty tank capacity tell-tale.
 28. The method as claimedin claim 18, wherein the measures involve an actuation of theelectrically adjustable outside rearview mirrors or the electricallyadjustable seats during standstill of the motor vehicle unwanted by thedriver.
 29. The method as claimed in claim 18, wherein the measuresinvolve switching on the dimmed headlight unwanted by the driver. 30.The method as claimed in claim 18, wherein the measures involveswitching off the power steering system unwanted by the driver.
 31. Themethod as claimed in claim 18, wherein the measures involve anadditional signal in a brake system with electronically adjustable brakeforces which influences the desired brake force to such effect that afluctuation of the longitudinal deceleration can be detected whichcorresponds in its mean value per unit time to the desired brake force,however.
 32. The method as claimed in claim 31, wherein the measuresinvolve a change of the pedal-travel/brake-force characteristics. 33.Device for implementing the method as claimed in claim 1, wherein acentral control unit is provided sensing the safety-relevant operatingconditions and triggering measures.
 34. The device as claimed in claim33, wherein the central control unit is integrated into an instrumentcombination device.